1. Field of the Invention
The present invention is related to an alternating current (AC) line emulator, and particularly to an AC line emulator that utilizes an automatic regulating load so that power consumption of the automatic regulating load is equal to a sum of output power of a grid-connected power generation system and output power of an AC power supply. It could prevent current from reversing to the AC power supply with the result that the AC power supply being shut down.
2. Description of the Prior Art
Generally speaking, in the field of renewable energy, the popularity of a grid-connected power generation system grows up because of its better economic benefits and less detrimental impact on the environment. A grid-connected power generation system is used for converting direct current (DC) power generated by itself into alternating current (AC) power for a utility grid through a DC/AC inverter. Before a manufacturer prepares to design a grid-connected power generation system, the manufacturer must perform a series of standard tests on the designed grid-connected power generation system to determine whether requirements of safety certifications are met. However, total voltage harmonic distortion of a utility grid may affect harmonic current of a grid-connected power generation system. In addition, when the AC power is injected into a utility grid from a grid-connected power generation system, the manufacturer must consider conditions of the utility grid and the influences on the grid-connected power generation system caused by the loads coupled to the utility grid.
In the prior art, diagnostic programs are used to test a grid-connected power generation system through a power resistor chamber and an AC power supply. However, to successfully perform the diagnostic programs on the grid-connected power generation system, a user must frequently control switches coupled to the power resistor chamber and carefully regulate output power of the AC power supply to ensure that the grid-connected power generation system operates under the desired conditions. For the user, the above mentioned testing process is tedious and likely to cause errors. Therefore, the prior art is not a good choice for testing the grid-connected power generation system.